Show algebraic 3 catastrophe to inscribe

　　 1621Year, feierma bought mathematician of an ancient time to lose time " arithmetical " law translation begins to grind read, after dying till him, people discovery is in this book about errant equation "X2 Y2=z2" all on that one page of integral solution, feierma wrote a paragraph of word with Latin: "What any counts is cubic, indecomposable the cubic metre that counts into two and, 4 when any counts square, indecomposable mix just 4 times when count for two. Generally speaking, any second power, divide square beyond, indecomposable into other two are the same as Ci Mi the sum. Indecomposable into other two are the same as Ci Mi the sum..

This paragraph of word, say with present mathematical language, namely: WhenNTo be more than2when integer, equationXn Yn=znHave integral solution impossibly. This is called namely 3 catastrophe inscribe latter-day maths one of " the Martha that expend Er is theorematic " . Come more than 300 years, a lot of mathematician are opposite this " theorematic " had a proof, gain headway in succession, until1993Year, mathematician proves Cai Weiying country by Huaiersiche. Of course, his proof still remains authoritative mathematician people examine carefully.

Bach of elder brother heart is Prussian clique an envoy toward Russia, later, he became a mathematician. He often believes discussion maths problem with Oulatong. 1742Year, bach of elder brother heart put forward to guess in the communication with Ou La. After the transmission of letter in reply of this letter and Ou La comes out, mathematician the question that raises in their communication, be called Bach of elder brother heart to guess: